A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The technical name is the perigee-syzygy of the Earth–Moon–Sun system. The term supermoon is not astronomical, but originated in modern astrology. The association of the Moon with both oceanic and crustal tides has led to claims that the supermoon phenomenon may be associated with increased risk of events such as earthquakes and volcanic eruptions, but there is no evidence of such a link.

The opposite phenomenon, an apogee-syzygy, has been called a micromoon, though this term is not as widespread as supermoon.

The most recent supermoon occurred on November 14, 2016. This was the closest supermoon since January 26, 1948, and will not be surpassed until November 25, 2034 The closest supermoon of the century will occur on December 6, 2052. The next supermoon will be on December 14, 2016.

Occasionally, a supermoon coincides with a total lunar eclipse. The most recent occurrence of this was in September 2015, while the next time will be in October 2033.

The black hole information paradox is a puzzle resulting from the combination of quantum mechanics and general relativity. Calculations suggest that physical information could permanently disappear in a black hole, allowing many physical states to devolve into the same state. This is controversial because it violates a commonly assumed tenet of science—that in principle complete information about a physical system at one point in time should determine its state at any other time. A fundamental postulate of quantum mechanics is that complete information about a system is encoded in its wave function up to when the wave function collapses. The evolution of the wave function is determined by a unitary operator, and unitarity implies that information is conserved in the quantum sense.

Planet Nine is a hypothetical large planet in the far outer Solar System, the gravitational affects of which would explain the unusual orbital configuration of a group of trans-Neptunian objects (TNOs) that orbit mostly beyond the Kuiper belt.

The hypothesis first took form in a 2014 letter to the journal Nature by astronomers Chad Trujillo and Scott S. Sheppard, who had inferred the possible existence of a massive planet from similarities in the orbits of the distant trans-Neptunian objects Sedna and 2012 VP113. On 20 January 2016, researchers Konstantin Batygin and Michael E. Brown at Caltech argued that a massive outer planet would be the likeliest explanation for the similarities in orbits of six distant objects. The predicted planet would be a super-Earth, with an estimated mass of about 10 times that of Earth (approximately 5,000 times the mass of Pluto), a diameter two to four times that of Earth, and a highly elliptical orbit that is so far away that it could take around 15,000 years to orbit the Sun.

On the basis of models of planet formation that might include planetary migration from the inner Solar System, such as the fifth giant planet hypothesis, the authors suggest that it may be a primordial giant planet core that was ejected from its original orbit during the nebular epoch of the Solar System’s evolution.